<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        function add(a, b) {
            console.log((a + b));
        }
        add(1, 3)

        let app = function (a, b, c){
            console.log((a + b * c));
        }
        app(2, 5, 8)

        let app2 = (a, b, c) => console.log((a + b * c))
        app2(2, 5, 8)

        let app3 = (a, b) => {
            console.log((a + b));
            console.log((a * b));
        }
        app3(3, 5)

        let app4 = () => console.log('hehe')
        app4()

        let app5 = x => console.log(x+1)
        app5()

        let app6 = (x, y) => x + y
        app6()

        let app7 = x => x + 2

        let user = {
            username: '森怕森透',
            app: function (){
                console.log(this.username);
            }
        }
        user.app()

        let user2 = {
            username: 'U咩',
            app: function () {
                setTimeout(function () {
                    console.log(this.username);
                })
            }
        }
        user2.app()

        let user3 = {
            username: '约定人',
            app: function () {
                setTimeout(() => {
                    console.log(this.username);
                })
            }
        }
        user3.app()


    </script>
</head>
<body>

</body>
</html>